I think the game design on this one was really good! I really liked that the last row moved slower than the first, which gave you a fair chance of hitting the rotten wood in that row. I also feel like more rotten wood spawned in the first row, which made it easier to remove the rotten wood in the later rows without hitting any good logs. Really clever :D
All-in-all a really unique and manageable idea for this three hours game jam. The execution was also great! Of course some sound and music would have been nice, but I am sure you know this :P As others have said, a bit more juice would be amazing if you decide to continue working on this. Like particles when you hit a log or when you shoot, etc. Another little thing is that sometimes I hit two chunks of wood at the same time, which sometimes felt a bit unfair when it removed a good log as well (although it removed bad logs an equal amount of times, so it may not be a bad thing :P)
Great submission! I really liked it :)